[Xen-devel] [PATCH v5 for-4.9 2/4] hvm/dmop: Implement copy_{to, from}_guest_buf() in terms of raw accessors

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

This allows the usual cases to be simplified, by omitting an unnecessary buf
parameters, and because the macros can appropriately size the object.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Paul Durrant <paul.durrant@xxxxxxxxxx>
CC: Julien Grall <julien.grall@xxxxxxx>
---
 xen/arch/x86/hvm/dm.c | 47 +++++++++++++++++++++++++++++------------------
 1 file changed, 29 insertions(+), 18 deletions(-)

diff --git a/xen/arch/x86/hvm/dm.c b/xen/arch/x86/hvm/dm.c
index 63d15ec..3d8ae89 100644
--- a/xen/arch/x86/hvm/dm.c
+++ b/xen/arch/x86/hvm/dm.c
@@ -37,36 +37,48 @@ struct dmop_bufs {
 #undef MAX_NR_BUFS
 };
 
-static bool copy_buf_from_guest(const xen_dm_op_buf_t bufs[],
-                                unsigned int nr_bufs, void *dst,
-                                unsigned int idx, size_t dst_size)
+static bool _raw_copy_from_guest_buf(
+    const struct dmop_bufs *bufs, unsigned int idx,
+    void *dst, size_t dst_bytes)
 {
-    size_t size;
+    size_t buf_bytes;
 
-    if ( idx >= nr_bufs )
+    if ( idx >= bufs->nr )
         return false;
 
-    memset(dst, 0, dst_size);
+    buf_bytes = bufs->buf[idx].size;
 
-    size = min_t(size_t, dst_size, bufs[idx].size);
+    if ( dst_bytes > buf_bytes )
+        return false;
+
+    memset(dst, 0, dst_bytes);
 
-    return !copy_from_guest(dst, bufs[idx].h, size);
+    return !copy_from_guest(dst, bufs->buf[idx].h, dst_bytes);
 }
 
-static bool copy_buf_to_guest(const xen_dm_op_buf_t bufs[],
-                              unsigned int nr_bufs, unsigned int idx,
-                              const void *src, size_t src_size)
+static bool _raw_copy_to_guest_buf(
+    struct dmop_bufs *bufs, unsigned int idx,
+    const void *src, size_t src_bytes)
 {
-    size_t size;
+    size_t buf_bytes;
 
-    if ( idx >= nr_bufs )
+    if ( idx >= bufs->nr )
         return false;
 
-    size = min_t(size_t, bufs[idx].size, src_size);
+    buf_bytes = bufs->buf[idx].size;
+
+    if ( src_bytes > buf_bytes )
+        return false;
 
-    return !copy_to_guest(bufs[idx].h, src, size);
+    return !copy_to_guest(bufs->buf[idx].h, src, src_bytes);
 }
 
+#define copy_from_guest_buf(bufs, buf_idx, dst) \
+    _raw_copy_from_guest_buf(bufs, buf_idx, dst, sizeof(*(dst)))
+
+#define copy_to_guest_buf(bufs, buf_idx, src) \
+    _raw_copy_to_guest_buf(bufs, buf_idx, src, sizeof(*(src)))
+
 static int track_dirty_vram(struct domain *d, xen_pfn_t first_pfn,
                             unsigned int nr, struct xen_dm_op_buf *buf)
 {
@@ -317,7 +329,7 @@ static int dm_op(domid_t domid, struct dmop_bufs *bufs)
     if ( rc )
         goto out;
 
-    if ( !copy_buf_from_guest(&bufs->buf[0], bufs->nr, &op, 0, sizeof(op)) )
+    if ( !copy_from_guest_buf(bufs, 0, &op) )
     {
         rc = -EFAULT;
         goto out;
@@ -573,8 +585,7 @@ static int dm_op(domid_t domid, struct dmop_bufs *bufs)
     }
 
     if ( (!rc || rc == -ERESTART) &&
-         !const_op &&
-         !copy_buf_to_guest(&bufs->buf[0], bufs->nr, 0, &op, sizeof(op)) )
+         !const_op && !copy_to_guest_buf(bufs, 0, &op) )
         rc = -EFAULT;
 
  out:
-- 
2.1.4


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel